1. Technical Field
The present invention relates to a method and apparatus for communications in dynamic networks such as ad-hoc and/or parasitic networks.
2. Related Art
A definition of an ad hoc network in “Routing in Ad Hoc Networks of Mobile Hosts”, D. B. Johnson, Proceedings of the Workshop on Mobile Computing Systems and Applications, pages 158-163, 1994, is “a collection of wireless mobile hosts forming a temporary network without the aid of any centralised administration or standard support services regularly available on the wide-area network to which the hosts may normally be connected”. In general ad hoc networks provide robust and adaptive solutions to a variety of wireless communications-related problems. Applications may be short or long-term solutions i.e. temporary or permanent networks.
“A survey of routing techniques for mobile communication networks”, S. Ramanathan and M. Steenstrup, ACM/Baltzer Mobile Networks and Applications, pages 89-104, 1996, discloses routing techniques specifically designed for fully mobile architecture (packet radio or ad hoc networks) in which a definition (and therefore a differentiation) is made between switches and endpoints in the network. These systems also define hierarchy of network nodes which in some cases is dynamic, whereby nodes can be assigned the function of a temporary base station. Although hierarchy is obviously an efficient way to ensure proper routing of messages throughout a network, it requires de facto that some non-local, sometimes complex information is stored in specialised nodes.
“An Efficient Routing Protocol for Wireless Networks”, S. Murthy and J. J. Garcia-Luna-Aceves, ACM Mobile Networks and Applications Journal, Special issue on Routing in Mobile Communication Networks, Vol. 1, No. 2, 1996, discloses a routing protocol in which no differentiation between switches and endpoints is present. This protocol is potentially more resource-consuming because it requires that routing tables are constantly updated around the system.
“Dynamic source routing in ad hoc wireless networks” in “Mobile Computing” D. B. Johnson and D. Maltz, (T. Imielinski and H. Korth, eds), chapter 5, Kluwer Academic Press, 1996, discloses a system called DSR. DSR has routing information traveling along with data packets and uses aggressive route discovery to keep the information up to date. However, as noted in “Ad hoc On-Demand Distance Vector (AODV) Routing”, C. E. Perkins, E. M. Royer and S. M. Das, July 2000, IETF Internet Draft (work in progress), all intermediate nodes are still required to store (and treat) routing information. Furthermore, DSR makes extensive use of flooding procedures to provide the source with an appropriate sequence of hops to the target. Although flooding speeds up the route discovery process, it is a potential cause for system breakdown due to overhead (for example when many sources are sending simultaneous requests).